In the field of toners for electrophotography, with the progress of electrophotographic systems, it has been demanded to develop toners adaptable for high image quality and high copying speed. From the viewpoint of the high image quality, the toners are required to have a small particle size, and the particle size and particle shape thereof must be suitably controlled.
As the method of controlling a particle size of the toners with a high accuracy and attaining a sharp particle size distribution and a sharp charge distribution thereof, there is disclosed, for example, the process for producing a toner for developing an electrostatic latent image by subjecting resin particles contained in a dispersion to salting-out/aggregation to form toner particles which process includes a step of adding a salting-out agent, in particular, a di- or more valent salting-out agent to the dispersion (salting-out/aggregation step), and a step of adding a salting-out stopping agent to the dispersion at the time at which the toner particles is grown such that a volume-average particle size thereof reaches from 2 to 9 μm (particle growth-stopping step) (refer to JP 2003-66648A).
Also, as the technique for controlling a shape of toner particles at a low temperature, there is known the method of substantially decreasing a glass transition point of resin particles by adding thereto an organic solvent capable of being infinitely dissolved in water to effectively conduct melt-bonding/fusion of the particles (refer to JP 2004-295028A). Further, there is known the emulsion polymerization and aggregation method in which a surfactant such as an alkylbenzenesulfonic acid is added during growth of particles to thereby obtain toner particles having a narrow dimensional distribution (refer to JP 7-146584A). In addition, JP 2002-131978A discloses the process for producing styrene-acryl-based toner particles by conducting salting-out, aggregation and fusion thereof under the coexistence of a specific surfactant.